2020J. Pl. Res. Vol. 18, No. 1, pp 157-162, 2020 Journal of Resources Vol.18, No. 1

Diversity of Phorophytes Selected by Epiphytic Orchid cristata Wall. ex Lindl. () in Central

Sangram Karki* and Suresh Kumar Ghimire Central Department of Botany, Tribhuvan University, Kirtipur, Kathmandu, Nepal *Email: [email protected]

Abstract

Epiphytic orchids, which live non-parasitically on another plant (host or phorophyte) are the important component of global plant diversity, and occurdiversely in tropical and sub-tropical forest of Nepal. However, little is known about the specificity of the relationship between epiphytic orchids and their host tree species in Nepal. Host specificity relationship was assessed for the epiphytic orchid Vanda cristata Wall. ex Lindl. in tropical and sub-tropical forest of Jugu, Central Nepal. To record the local abundance and geographical distribution, a rating system was used. The result showed that majority of orchid-host associations were locally sparse and restricted geographically (42.10 %), followed by locally sparse and widespread (21.05 %). Vanda cristata was seen as generalist species because it was found colonized on 19 different host tree species (phorophytes). Thus, non-specific nature of association of this orchid with host trees was detected.

Keywords: Epiphytes, Host species, Host specificity

Introduction impermeable cuticles, which help them to adapt successfully even in the poor nutrient and water Epiphytes, which contribute about 10 percent of total supply conditions and led them to an outstanding vascular species (Kress, 1986) are diverse and success in epiphytic habitat (Zotz & Winkler, 2013). important component of global plant diversity. They live on another plant (host plant or phorophytes) for Epiphytic orchids constitute an important position the structural support and anchorage, thus known as in the flora of Nepal. So far, 256 species of epiphytic structurally dependent (Wagner et al., 2015). orchids have been discovered from the country, and Epiphytic orchids, which belongs to the family still are in the process of documentation Orchidaceae, includes some threatened species and (Rajbhandari & Rai, 2017; Shrestha et al., 2018; encompass up to 70% of total vascular epiphytic Raskoti & Ale, 2019). They are distributed from 60 species (Madison, 1977), occur diversely in tropical m to 5200 m asl in Nepal (Rokaya et al., 2013), and subtropical forest of the world (Nieder et al., growing on various habitats and microclimatic 2001). conditions. Most of the epiphytic orchids occur in tropical and sub-tropical forests of the country Epiphytes are broadly classified into two groups: (Acharya et al., 2011). holo-epiphytes (spending their entire life on the host tree) and hemi-epiphytes (spending only part of their Studies on host specificity analysis are very few in life cycle on host tree) (Benzing, 1990; Nieder et the Nepalese context. In other parts of the world, al., 2001; Bhatt et al., 2015). Epiphytic orchids are studies have shown that epiphytic orchids have host vascular holo-epiphytes. Due to complex habit, preference and that depends on the host traits perfect suit of environment is necessary for their (Callaway et al., 2002; Merwin et al., 2003). It has survival and growth. Therefore, to adapt in epiphytic been suggested that successful seedling habit, they have developed some special establishment on a phorophyte depends on biotic and morphological and physiological adaptations. For abiotic factors like tree bark roughness, host size, example, succulent leaves and stems, pseudobulb bark porosity, height, bark chemistry (e.g., pH, plant as storage organ, sunken stomata, CO2 uptake via. exudates) and suitable mycorrhizae (Johanson, 1974; CAM pathway, roots with velamen redicum and Callaway et al., 2002; Trapnell & Hamrick, 2006;

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Adhikari & Fischer, 2011). Trapnell & Hamrick powder as expectorant (Manandhar, 2002; Subedi (2006) suggested that presence of suitable et al., 2013). Similarly, the plant bear attractive mycorrhizae is the most critical factor because orchid flowers, so used as ornamental plant in home seed lacks endosperm and requires suitable gardens. Thus, concerning the diverse use-values, mycorrhizal infection for carbon uptake before this species is recognized asone of the most germination. This study is aimed to assess the important orchid species of Nepal. diversity of phorophytes colonized by epiphytic orchid Vanda cristata in tropical and sub-tropical Study area forest of Central Nepal. The study was carried out in tropical and sub-tropical forest of Jugu (now Gaurishankhar Rural Materials and Methods Municipality) Central Nepal, with coordinate between 27º 53' N to 27.88º N latitudes and 86º 24' Study species E to 86.40º E longitudes (Figure 2). The climate Vanda cristata is the perennial epiphytic orchid first ranges from warm tropical, subtropical monsoon and collected in 1818 AD by Nathaniel Wallich in Nepal cool temperate. There is high rainfall during and described by John Lindley in 1832. It is monsoon period (June to September) and account distributed in Bhutan, Nepal, , N. Vietnam, for about 80 percent of the total annual rainfall. Thailand, Myanmar, Bangladesh and According to the report of the nearest Jiri weather (geographical distribution) (Roskov et al., 2019). In station, the area receive an average precipitation of Nepal, it is distributed in Central and Eastern Nepal 2427.817 mm. The annual mean minimum and from 920 m to 2300 m (Rajbhandari & Rai, 2017). maximum temperature are 8.17°C and 20.71°C, It is monopodial epiphytic orchid (holo-epiphyte) respectively (Karki, 2019). with yellowish-green fragrant flowers (Figure 1). Single inflorescence can produce 1 to 3 flowers and usually 1 or rarely 2 healthy pods. Flowers are thickly textured with wide openings. Petals are falcate, lip golden yellow to white, three-lobed and spurred. This species loves middle and lower trunks of host trees. Flowering time of V. cristata is from May to July.

Figure 1. Study species Vanda cristata Wall. ex Lindl.

Vanda cristata Wall. ex Lindl. has medicinal importance. The paste prepared from the root is used to treat dislocated bones, cut and wounds and leaf Figure 2: Map of Dolakha district showing study area

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Data collection systematically studied. Most common host species The study was based on both repeated field surveys colonized by V. cristata was Prunus cerasoides and literature reviews. Observations of different (Rosaceae). However, V. cristata was also frequently forest types (e.g., sal forest, riverine forest, Schima- observed on Shorea robusta, Ficus nerifolius and Castanopsis forest and mixed pine forest) of Jugu Schima wallichii. The association of Vanda cristata were systematically made. The population of with multiple host species indicated that, it has high epiphytic orchid Vanda cristata along with their host ability to establish population on several trees and locations were recorded. The variety of phorophytes, which is a good emblem of long-term phorophyte species colonized by Vanda cristata was survival potential of this species. photographed and identification of host species was These results concur with the distribution of another made. The family of each host species was also epiphytic orchid species Rhynchostylis retusa, which identified. is morphologically similar with V. cristata (Adhikari In each site, the number of host individuals & Fischer, 2011). In many host species, V. cristata supporting Vanda cristata was recorded. A method was observed at only once in the study sites. known as rating system (Trapnell & Hamrick, 2006), Although, there was good abundance of other trees similar to that of Rabinowitz (1981), was used to (Pinus roxburghii, Dalbergia sissoo and Myrica account the local abundance of host trees supporting esculenta) in the study sites, but we didn’t find the V. cristata and geographical distribution of that association of V. cristata on those tree species. It orchid-host association (Table 1). In this method, seems unlikely that seed of V. cristata doesn’t fall based on the abundance of epiphytic orchid on host on the trunk of those trees, but it is predictable that trees, theirlocal status was categorized into three such trunk lack appropriate substrate and different categories viz. locally abundant (A), locally mycorrhizae for the germination of V. cristata sparse (S) and locally occasional (O). For occurrence seedlings. of V. cristata on a particular tree species to be rated The result showed that the abundance of V. cristata as ‘A’; several to many individuals of that tree on host trees at locality were locally sparse (63.15%), species had to support V. cristata at each site. A rating of which majority of orchid-host associations were ‘S’ indicates that, if only few individuals of that tree locally sparse and restricted geographically (8 species support V. cristata at each site. Similarly, species, 42%), followed by locally sparse and rating ‘O’ was given in cases where some locations widespread (4 species, 21.05%) (Table 2).Twelve had less than three trees with orchids, while other associations were seen as locally sparse (63.15%), locations had many trees of that species supporting of which four (21%) were widespread and eight V. cristata (Trapnell & Hamrick, 2006). Similarly, (42.10%) were recorded within restricted following Trapnell & Hamrick (2006), the geographical range (Table 1 and 2). Similarly, three geographic distribution of trees having V. cristata species have restricted and occasional distribution was recorded for each host/ phorophyte species as (15.78%) and two species have wide spread and widespread (W) or restricted (R). A rating ‘W’ locally abundant distribution (10.52%) (Table 1). indicated that, the host tree has wide distribution, This indicates, although V. cristata have wide range whereas rating ‘R’ indicated the narrow distribution of host species, the abundancewas locally sparse and of host species in the study area. distribution was restricted to few sites only. Sparse local abundance of V. cristata in some sites was due Results and Discussion to the sparse occurrence of host tree species (For Vanda cristata was found colonized on 19 different example: Ficus carica, F. sarmentosa and Fraxinus host species (Table 2). This shows V. cristata is not floribunda). These findings agree with the findings host-specific orchid species. Although, this number of Trapnell & Hamrick, (2006) on the host-orchid is not exact because many areas were not associations of neotropical orchid Laelia rubescens.

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However, in our study locally abundant V. cristata epiphytic orchid species, such as Vandopsi also have restricted geographical distribution (5.26 sundulata, Oberonia pachyrachis, Pholidota %), which differ from previous result of Trapnell & articulata and Dendrobium heterocarpum and hemi- Hamrick, (2006). parasitic species, such as Hoya linearis, Lepisorus sp., Scrrula elata, and Drynaria mollis. In addition, it was observed that V. cristata was also found in degraded habitat. Thus, it is predictable that Table 2: Phorohyte species of epiphytic orchid Vanda cristata Vanda cristata can tolerate some level of Wall. ex Lindl. disturbances and pollution. Vanda cristata has large, Occurrence of S.N Phorophyte Family Vc long roots and thick leaves, which might be association 1. Acacia catechu Fabaceae RS advantageous to tolerate some degree of 2. Alnus nepalensis Betulaceae WS disturbances.In general, our study supports the 3. Buddleja asiatica Scrophulariaceae RO previous findings, such as large-sized trees supports 4. Engelhardia spicata Juglandaceae WS more species, high bark rugosity supports many 5. Euphorbia royelena Euphorbiaceae RS 6. Eurya acuminata Theaceae WS species (Callaway et al., 2002; Hirata et al., 2008). 7. Ficus carica Moraceae RS Regardless, many individuals were seen adapted 8. Ficus nerifolius Moraceae RS successfully even on trees with less rugose bark and 9. Ficus religiosa Moraceae WO on branches of small size. In some trees, even small 10. Ficus sarmentosa Moraceae RS 11. Fraxinus floribunda Oleaceae RS twig (less than 10 cm diameter) also supported many 12. Juglans regia Juglandaceae WS individuals. It indicate that, in particular site, host 13. Mangifera indica Anacardiaceae RO bark rugosity and host size are less important for 14. Prunus cerasoides Rosaceae WA the occurrence of V. cristata. Other various 15. Quercus glauca Fagaceae RS 16. Sarauria napaulensis Sarauriaceae RO microclimatic factors might be responsible for their 17. Schima wallichii Theaceae WA occurrence in those sites. 18. Shorea robusta Dipterocarpaceae RA 19. Wendlandia heynei Rubiaceae RS In most of the study sites, V. cristata was recorded Note: RS = Restricted, locally sparse, WS = Widespread, locally in the lower and middle trunk zones of host trees sparse, RO = Restricted, locally occasional, WO = Widespread, forming a patchy populations, covering the host locally occasional, WA = Widespread, locally abundant, RA = trunk by their large roots, indicating that these layers Restricted, locally abundant are suitable for the growth. The reason behind the Conclusion successful establishment of V. cristata on lower layer of host tree might be due to high substrate stability From the result, Vanda cristata showed generalist and moisture in lower trunk layers compared to upper behavior and tend to establish population on more layers. They are normally associated with other than single host species rather than on a particular

Table 1: Frequency of epiphytic orchid Vanda cristata (Vc) found on phorophytes locally and over the orchid’s geographical range in forest of Central Nepal. Percentages are of 19 host tree species (see table 2) supporting Vc in each classification.

Abundance of Vc on Geographical range of Phorophytes/ Vc association phorophytes at locality Widespread (W) Restricted (R) Locally abundant (A) Vc on many trees locally. Association Vc on many trees locally. Association with with phorophyte widespread phorophyte restricted geographically to one or geographically. (10.52 %) few sites. (5.26%) Locally occasional (O) Vc on varying numbers of trees locally. Vc on varying numbers of trees locally. Association with phorophyte widespread Association with phorophyte restricted geographically. (5.26 %) geographically to one or few sites. (15.78 %) Locally sparse (S) Vc on one to a few trees locally. Vc on one to a few trees locally. Association with Association with phorophyte widespread phorophyte restricted geographically to one or geographically. (21.05 %) few sites. (42.10%)

160 2020 Journal of Plant Resources Vol.18, No. 1 host species. Therefore, it seems that the future biogeography of neotropical vascular epiphytes. perpetuation potential of this species is high, Ann. Missouri Bot. Gard, 74, 205–233. although orchid-host associations were locally sparse Hirata, A., Kamijo, T. & Saito, S. (2008). Host trait and restricted geographically in the study area. Host preferences and distribution of vascular epiphytes preference was biased towards the host trees having in a warm temperate forest. Plant Ecology, 201, thick, rugose bark and tree withlarge size. However, 247–254. different underlying mechanisms might be there for the successful host-epiphyte associations and host Johansson, D. (1974). Ecology of vascular epiphytes preference. Therefore, future research work should in West African rain forest. Acta use a comprehensive approach for determining host Phytogeographica Suecica, 59, 1–123. traits, the role of mycorrhizae and microclimatic Karki, (2019). Diversity, Distribution and conditions in order to give some rigorous Ethnobotany of Epiphytic Orchids in Jugu, conclusions about the host specificity. Dolakha, Central Nepal. (Master’s Dissertation). Central Department of Botany, Tribhuvan Acknowledgements University, Kirtipur, Kathmandu, Nepal. Authors would like to acknowledge the head of Kress, W.J. (1986). The systematic distribution of Central Department of Botany for the administrative vascular epiphytes: an update. Selbyana, 9, 2– support. The help of local peoples in the field are 22. highly acknowledged. Madison, M. (1977). Vascular epiphytes: their systematic occurrence and salient features. References Selbyana, 2, 1–13. Acharaya, K.P., Vetaas O.R. & Birks H.J.B. (2011). Manandhar, N.P. (2002). Plants and people of Nepal. Orchid speciesrichness along Himalayan Oregon, USA: Timber Press Portland. elevational gradients. Journal of Biogeography, Merwin, M.C.,Rentmeester, S.A. & Nadkarni, N. M. 38(9), 1821–1833. (2003). The influenceof host trees species on the Adhikari, Y.P. & Fischer, A. (2011). Distribution distribution of epiphytic bromeliads in pattern of the epiphytic orchid experimental monospecific plantations, LaSelva, Rhynchostylisretusa under strong human Costa Rica. Biotropica, 35, 37–47. influence in Kathmandu valley, Nepal. Botanica Nieder, J., Prosperi, J. & Michaloud, G. (2001). Orientalis- Journal of Plant Science, 8, 90–99. Epiphytes and their contributionto canopy Benzing, D.H. (1990). Vascular Epiphytes. diversity. Plant Ecology, 153, 51–63. Cambridge, UK: Cambridge University Press. Rajbhandari, K.R. & Rai, S.K. (2017). A Handbook Bhatt, A., Gairola, S., Govender, Y., Baijnath, H. & of of Nepal, Vol.1. Kathmandu, Ramdhani, S. (2015). Epiphyte diversity on host Nepal: Department of Plant Resources. trees in an urban environment, eThekwini Raskoti, B.B. & Ale, R. (2019). New species of Municipal Area, South Africa. New Zealand orchids and notes on Orchidaceae of Nepal. journal of botany, 53(1), 24–37. Phytotaxa, 394(4), 257–266. Callaway, R.M., Reinhart, K.O., Moore, G.W., Rabinowitz, D.(1981). Seven forms of rarity. Pp. Moore, D.J. & Pennings, S.C. (2002). Epiphyte 205–218 In H. Spunge, ed. The Biological host preferences and host traits: mechanisms for Aspectsof Rare Plant Conservation, New York: species-specific interactions. Oecologia, John Wiley and Sons. 132,221–230. Rokaya, M.B., Raskoti, B.B., Timsina, B. & Gentry, A.H. & Dodson,C.H. (1987). Diversity and Mu¨nzbergova´, Z. (2013). An annotated

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checklist of the orchids of Nepal. Nordic Journal (2013). Medicinal use and trade of wild orchids of Botany, 31, 511-550. in Nepal. Journal of Ethnobiology and Roskov, Y., Ower, G., Orrell, T., Nicolson, D., Bailly, Ethnomedicine, 9(1), 64. N., Kirk, P.M., Bourgoin, T., DeWalt, R. E., Trapnell, D.W. & Hamrick, J.L. (2006). Variety of Decock, W., Nieukerken, E. van, Zarucchi J. & phorophyte species colonized by the neotropical Penev L., Eds. (2019). Species 2000 & ITIS epiphyte, Laeliarubescens (Orchidaceae). Catalogue of Life, 2019 Annual Checklist. Digital Selbyana, 27(1), 60-64. resource at www.catalogueoflife.org/annual- Wagner, K., Mendieta-Leiva., G. & Zotz, G. (2015). checklist/2019. Species 2000: Naturalis, Leiden, Host specificity in vascular epiphytes: a review the Netherlands. ISSN 2405-884X. of methodology, empirical evidence and potential Shrestha, K.K., Bhattarai, S. & Bhandari, P. (2018). mechanisms. AoBPLANTS,7, plu092; Handbook of Flowering Plants of Nepal: doi:10.1093/aobpla/plu092. Gymnosperms and Angiosperms: Cycadaceae- Zotz, G. & Winkler, U. (2013). Aerial roots of Betulaceae, Vol. 1. Jodhpur, India: Scientific epiphytic orchids the velamen redicum and its Publishers. role in water and nutrient uptake. Oecologia, 171, Subedi, A., Kunwar, B., Vermeulen, J.J., Choi, Y., 733–741. Andel, T., Chaudhary, R.P. & Gravendeel, B.

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